This invention relates to method and apparatus for manufacture of thin sheet glass by redrawing material sheet glass (glass sheet reforming method).
Thin sheet glass with a thickness of 1 mm or less to be used in liquid crystal display glass, cover glass of a solar battery, cover glass of CCD, cover glass of LED, and others may be warped, bent or creased and poor in surface precision if manufactured by ordinary sheet glass manufacturing methods such as the full course method and the slit-down method. As the thin sheet glass manufacturing method to eliminate such disadvantages, the sheet glass reforming method is known (for example, the Japanese Patent Publication No. 59-4383).
In this sheet glass reforming method, the material sheet glass of a thick wall (for example, thickness of 5 mm) is heated over the softening temperature, and it is drawn to reform the section thinly (e.g. thickness: 0.1 to 0.03 mm). According to this reforming method, by varying the feed speed of the material sheet glass, heating capacity, or pulling speed, a desired sheet thickness will be easily obtained.
The material sheet glass used in this sheet glass reforming method is preliminarily cut to a specific length, and each sheet is fed into the reforming device by chucking its upper end, and therefore the chucked portion is not heated and softened, and the rate of use of the material sheet glass is lowered by that portion. Besides, since the material sheet glass is intermittently fed into the reforming device one by one in a batch system, the temperature of the heating furnace may vary until the next material sheet glass is supplied, and the sheet drawing condition may be discontinuous, and hence it is difficult to obtain a homogeneous thin sheet glass.